1. Field of the Invention
The present invention relates to a method and device for inspecting a wafer for the deposition of foreign matter.
2. Description of the Related Art
A wafer is formed with a plurality of devices such as ICs and LSIs, and these devices are partitioned by a plurality of streets. The wafer is cut by dicing along these streets to obtain the individual devices. Each device is mounted on a lead frame or the like and next packaged to be used in various electronic equipment. The surface of each device is formed with a plurality of electrodes arranged along each street, so as to allow the electrical connection with the lead frame.
However, there is a possibility that foreign matter such as cutting dust and grinding dust may be deposited to the devices during the fabrication steps, causing a reduction in quality of the devices due to the deposited foreign matter. To cope with this possibility, there has been proposed a method of detecting the deposited foreign matter such as cutting dust (see Japanese Patent Laid-open No. 11-173993, for example).
However, the scale of integration in each device is increased to result in size reduction. With such size reduction, the space between the electrodes becomes as small as 50 to 10 μm, for example. Accordingly, there arises a problem such that foreign matter such as cutting dust may be deposited over the adjacent electrodes to cause a short circuit between these electrodes. Further, checking the wafer for deposited foreign matter by using a microscope or the like is inefficient to cause a reduction in productivity.